Electrical contact actuating device for use in a crossbar switch



Jan. 16, 1968 L P JR 3,364,447

ELECTRICAL CONTACT ACTUATING DEVICE FOR USE IN A CROSSBAR SWITCH Filed April 19, 1965 2 Sheets-Sheet l //Vl/E/V7'0/? ROBERT L. PEEK JR.

AGENTS ell/1 15 5 smz w Jan. 16, 1968 R. L. PEEK, JR 3,3 7

ELECTRICAL CONTACT ACTUATING DEVICE FOR USE IN A CROSSBAR SWITCH Filed April 19, 1965 2 Sheets-Sheet 2 //WE/VTO/? ROBERT L. PEEK JR.

AGENTS law/ q lwl oy Unite States Patent Canada Filed Apr. 19, 1965, Ser. No. 449,151 12 Claims. (Cl. 335-112) ABSTRACT 9F THE DISCLUSURE An electrical contact actuating device for use in the crosspoint selecting mechanism of a crossbar switch. A select bar rotatable in opposite directions about its longitudinal axis on operation of a select magnet carries rigid L-shaped members each interposed between a pair of separately supported finger members such that the finger members are in the path of rotation of the rigid members. The shanks of each pair of finger members are interposed between a pair of actuating cards and an actuator which is movable toward the cards on operation of hold magnet. The finger members are centered about a slot in the actuator such that when the actuator is moved toward the cards it will not engage the finger members when they are in their unoperated positions. Each card is provided with a pair of surfaces facing the actuator having a slot therein such that a shoulder of the actuator can move into the slot when an associated finger member is in its unoperated position. When a finger member is in its operated position and the actuator is moved toward the cards, the finger member is trapped between a surface of the actuator and the surfaces of the card across the slot to move the card and operate the crosspoint. The actuator is provided with surfaces on each side of its slot which tion of their associated finger members such that if the slope away from the cards toward the direction of operaactuator is already operated due to operation of the hold magnet and the select bar is then operated by the select magnet, an operated finger member can move substantially its operated distance along its associated sloping surface of the actuator.

My invention relates to a switch and is particularly adaptable for use in the crosspoint selecting mechanism of a communications crossbar switch.

Crossbar switches are widely used in communication switching systems for interconnecting large numbers of electrical circuits. In a typical crossbar switch, a number of so-called select magnets are. each associated with one horizontal level of crosspoints. Operation of a select magnet causes a horizontal select bar to rotate about its longitudinal axis. The select bar carries a number of elongated, resilient finger members which rotate with the select bar into their operated positions at all crosspoints in that level. A number of so-called hold magnets are each associated with a vertical column of crosspoints. When a finger member is in its operated position it is interposed between the hold magnet actuator of the vertical column and the crosspoint card at the horizontal level. During subsequent operation of the hold magnet of a vertical column its actuator causes the one operated finger member in that column to move against the crosspoint card in that horizontal level. Movement of the card operates the crosspoint containing a number of pairs of spring contacts. The finger member is held by the actuator in this operated crosspoint and the remaining finger members of this level are returned to their normal position by the select bar upon release of the select magnet. Subsequent release of the hold magnet releases the selected crosspoint and the released finger member returns to its normal position. A typical prior art crossbar switch is disclosed in Canadian Patent No. 3603076 to J. N. Reynolds, the teachings of which are hereby incorporated by reference.

It has been found convenient to use a single select bar for each adjacent pair of select magnets and their associated levels. Rotation of the select bar in two directions about its longitudinal axis permits rotation of the finger members into their operable position in each of the two adjacent levels.

It is important that crossbar switch contacts of the selected crosspoint operate quickly and that the correct crosspoints are selected if eflicient and economical communications service is to be provided. Known crossbar switches of the type briefly referred to above have proven fast in operation but difiiculties have been encountered in ensuring accurate positioning of the finger members for crosspoint selection. These finger members by necessity are quite flexible and require only a small amount of energy to cause them to vibrate with such a wide amplitude that a wrong crosspoint could be selected. One known way to avoid wrong crosspoint selection was to cause the control circuitry of the switch to provide a delay after operation of the select magnet to allow the vibration of the finger member to cease before operation of the hold magnet.

The finger members also tended to vibrate upon return to their normal position after release of the select or hold magnets. This has been overcome in the past by providing a vibration damping. device for the select finger and by causing the control circuitry of the switch to pro-- vide delays following the release of the select and hold magnets before subsequent switch operations were started.

The problem with introducing the above-mentioned dc" lays was that the trafiic capacity of the crossbar switches were reduced. Known vibration damping devices for the finger members using impact damping or deflection techniques have not been completely successful. Typical prior art vibration damping techniques are disclosed in U.S. Patents 2,039,630 and 2,827,518 to J. A. Burwell.

When known crossbar switches were assembled, the select bar had to be carefully placed in position with respect to the individual crosspoint actuators and careful adjustments made to ensure correct crosspoint selection. These adjustments were difiicult to make once the select bar was mounted because of the confined working space available. This problem was compounded when miniaturized switches were involved.

I have invented a switch that uses the well known principle of a resilient finger member to prepare the switch for selection of a crosspoint while reducing the above-mentioned problems caused by vibration of the finger member. In addition, my invention provides for relatively simple assembly and adjustment of a crossbar switch. My invention is also well adapted for use in miniature crossbar switches where close limits of accuracy in a confined space are required during manufacture.

According to my invention, I have provided a switch comprising resilient means arranged when flexed in one direction to condition the switch for operation, and control means mounted independently of the resilient means and operable to flex the resilient means in the direction mentioned.

In my preferred embodiment, the resilient means comprises an elongated finger member having one end attached to a support member, and the control means comprises an elongated rigid member having one end attached to a movable bar. The movable bar is arranged to rotate in the direction mentioned about its longitudinal axis. The rigid member is attached to the movable bar so that it will rotate with rotation of the movable bar As the rigid member rotates, it flexes the finger member and this positive action by the rigid member mounted independently of the select finger reduces the tendency of the finger member to vibrate as it did when mounted directly on the movable bar. This eliminates separate impact damping for the finger member when the finger member returns to its normal unoperated position. With the movable bar in its normal position, the rigid member acts as a stop to provide damping for the finger member.

With the problem of vibration reduced, in accordance with my invention, the traific carrying capacity of a crossbar switch can be increased by reducing the delay between the operation of the select magnet and the hold magnet, and between the release of these magnets and commencement of further switch operations.

With the finger members mounted independently of the rigid member and hence of the select bar of a crossbar switch, the finger members can be located with respect to the crosspoint actuators and adjusted on a sub-assembly basis, thereby making the job of adjustment easier. The adjustment of the rigid member at the time the select bar is mounted on the switch is a coarser adjustment and therefore relatively easier to achieve. The advantages of adjusting on a sub-assembly basis becomes more apparent in the design of a miniature crossbar switch.

My invention further retains the advantage of using a single select bar for each adjacent pair of select magnets and their associated levels by providing two finger members. One is disposed on each side of the rigid member which rotates with the select bar.

While the advantages of my invention have been discussed in connection with a crossbar switch, it will be understood by those skilled in the art that the principles of the invention are equally applicable to any switch within which a resilient means is arranged to be flexed to condition the switch for subsequent operation.

A preferred embodiment of my invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIG. 1 shows a three dimensional view of a portion of a crossbar switch in its unoperated condition; and

FIG. 2 shows the same view with a finger member of the switch in its operated position.

FIG. 1 shows part of a crossbar switch having a first pair of contacts 11} and 11 with contact being movable to mate with contact 11. Actuating means are shown as a first crosspoint card 12 and an actuator 13 arranged to move through a prescribed path that intersects the contact 10. The card 12 contains a first slot 1 4 into and out of which the actuator 13 is normally free to move. The card 12 contains a second slot 15 containing the contact 10. The contact 10 is preferably tensioned toward the contact 11 so that the contacts will mate with a predetermined pressure. The card 12 can be supported by balancing springs which normally hold the contacts 10 and 11 apart by urging the wall 16 against the contact 10..

In accordance with my invention, resilient means are shown as a first elongated finger member 17 having one end attached to a support member 18. Control means are shown as a substantially L-shaped, elongated rigid member 19 having one end attached to a movable bar 20 that is arranged to rotate about its longitudinal axis in a first direction as shown by the arrow 21. It is to be noted that the rigid member 19 is mounted independently of the finger member 17.

The finger member '17 is arranged to condition the switch for operation in the following manner: rotation of the movable bar 20 in the direction 21 (by external means not shown) urges the rigid member 19 against the finger member 17. This causes the finger member 17 to flex (see FIG. 2) and rest against a shoulder 26 of the actuator 13 in its path of travel toward the slot 14. The positive urging action of the rigid member 18 against the finger member 17 reduces undesirable vibration effects.

When the actuator 13 is subsequently moved in the direction of the arrow 22 (by external means not shown), the flexed finger member 17 is trapped between a surface 27 of the actuator 13 and the surfaces 28 of the card 12 which blocks the shoulder 26 of the actuator 13 from entering the slot 14. Continued movement of the actuator 13 in the direction of the arrow 22 causes the finger member 17 to move the card 12 a suificient distance so that the wall 16 no longer acts against the tension of the contacts 10 and 11, thereby allowing them to mate with each other.

The movable bar 21), carrying the member 19, can then be returned to its normal position. When the actuator 13 is subsequently returned to its normal position by movement in the direction of the arrow 23 (see FIG. 1), the rigid member 19 acts as a stop for the finger member 17 to damp further vibration.

The movable bar 21 can be arranged to rotate in the opposite direction as shown by the arrow 24 and an additional finger member 17a, crosspoint card 12a, and contacts 10a, 11a provided. Thus flexing of the finger member 17a by the rigid member 19 conditions the switch for subsequent mating of the contacts 10a, 11a. The rigid member 19 again provides damping for the finger member 17 a.

When my invention is used in a crossbar switch, a number of movable bars 20 would serve as the select bars at various horizontal levels and would each contain a number of rigid members 19, one being associated with a pair of finger members 17, 17a, a pair of contact carrying crosspoint cards 12, 12a and an actuator 13. The select bars 2t would be operated by their select magnets and the actuators 13 would be operated by their hold magnet armatures in a vertical'column in the well known manner. When the finger members 17 and 17a are in their unoperated positions, they are centered about a slot 25 of the actuator 13 so that the latter does not engage the finger members when it is moved in the direction of the arrow 22. The shoulders 26, 26a can thus move into the slots 14, 14a without causing movement of the cards 12, 12a or the contacts 10,10a. The select bars 20 are returned to their normal unoperated position on release of their select magnets by restoring springs in the well known manner. In a practical crossbar switch, the cards 12 and 12a would be extended to contain a number of pairs of contacts such as 10 and 11 to form what is known as a crosspoint.

Slot 25 of the actuator 13 is formed by surfaces 29, 29a extending and sloping away from associated surfaces 27, 27a from a position adjacent to, but spaced from, the unoperated positions of the finger members 17, 17a in a direction toward their respective operated positions. The surfaces 29, 29a are joined by a surface 30 at locations remote from their juncture with surfaces 27, 27a.

With finger member 17 trapped betwen surface 27 of operated actuator 13 and surfaces 28 of the card 12 (see FIG. 2), contacts 10 and 11 are mated with each other. As pointed out above, movable bar 20 can then be returned to its normal position. But movable bar 20 can be rotated in the direction of arrow 24 whileactuator 13 is still operated. As clearly shown in FIGURE 2, finger member 17a, which will be flexed by the member 19, will move substantially its operated distance along surface 29a without disturbing its associated card 12a from its unoperated position.

As mentioned above, when used in a crossbar switch, each movable bar 20 will contain a number of rigid members 19 each associated with a pair of finger members '17, 17a, a pair of cards 12, 12a and an actuator 13. Thus, if any actuator 13 associated with a movable bar 20 is operated and the bar is rotated, the operated finger member associated with the operatedactuator 13 will move along surface 29 or 29a without impedance. This situation would occur when a hold magnet in a vertical column is operated and a select magnet in any horizontal level is then operated. Or it may occur when actuator 13 of FIG. 2 has operated in direction 22 in connection with the operation of bar 20 in direction 21 to operate contacts 10 and 11, and bar 20 is subsequently rotated in direction 24.

As mentioned above, my invention can be used to facilitate the assembly and adjustment of a crossbar switch on a sub-assembly basis. Each support member 18 which carries the finger members 17 and 17a can be conveniently mounted on the hold magnet core in a vertical column of the switch for structural support. Bending adjustment can be easily made to correctly locate each finger member in its associated actuator slot 25.

Each pair of finger members 17, 17a can be bent outwardly at their supported end to form a V to facilitate introduction of the select bar rigid members 19 during assembly. The finger members 17 and 17a are tensioned against each side of the base of the L of their associated rigid member 19. This base is made of sufficient length to provide ample tolerance in the longitudinal location of the select bar 20.

The switch of my invention has been shown to satisfy a need for reducing the problems caused by vibration of elongated, resilient finger members. A crossbar switch is now available which can be adapted to carry more traflic due to the reduction in the delays on the operation and release of the select and hold magnets. The switch of my invention has been further shown to be advantageously suitable for assembly and adjustment on a sub-assembly basis.

What is claimed is:

1. An electrical contact actuating device for use in a crossbar switch comprising:

(a) a pair of electrical contacts, one contact being movable to mate with the other;

(b) a contact actuating card cooperating with said one contact, said card having an unoperated and an operated position and being movable between said positions through a prescribed path that intersects said one contact such that said contacts are spaced apart when said card is in its unoperated position and said contacts mate when said card is in its operated position;

(c), an actuator having an unoperated and an operated position and being movable between said positions through a prescribed path parallel to the prescribed path of said card;

((1) a support member and an elongated resilient finger member having one end attached to the support member, said finger member having its shank interposed between said actuator and said card across their prescribed paths, said finger member having an unoperated and an operated position and being movable a predetermined distance between said positions through a prescribed path at substantially a right angle to the prescribed paths of said actuator and said card;

(e) control means mounted independently of said finger member comprising a movable bar having an unoperated position and an operated position and arranged to rotate about its longitudinal axis in one direction between said positions, and an elongated rigid member having one end attached to the movable bar such that it will rotate with rotation of the movable bar, said finger member being located in the path of rotation of said rigid member such that said finger member is flexed from its unoperated to its operated position upon rotation of the movable member from its unoperated to its operated position; (f) said actuator and said card having surface means for cooperation with said finger member, such that said actuator when moved from its unoperated to its operated position when said finger member and said card are in their unoperated positions Will not engage said finger member, movement of said actuator from its unoperated to its operated position when said finger member is in its operated position will trap said finger member between said actuator and said card to cause said card to move from its unoperated to its operated position, and movement of said finger member from its unoperated to its operated position once said actuator is in its operated position will permit said finger member to move substantially said predetermined distance without engaging said card.

2. A device as defined in claim 1 wherein the surface means of said actuator comprises a first surface parallel to the prescribed path of said finger member and facing said card for trapping said finger member between said surface and said card when said finger member is in its operated position and said actuator is then moved from its unoperated to its operated position, and a second surface extending from said first surface and sloping away from said card from a position adjacent the unoperated position of said finger member in a direction toward the operated position of said finger member for permitting said finger member to be moved substantially said predetermined distance along said second surface once said actuator is in its operated position, said finger member being located adjacent to the juncture of said surfaces to permit movement of said actuator to its operated position past said finger member without engaging said finger member.

3. A device as defined in claim 2 wherein the surface means of said card comprising two coplanar fiat surfaces with a first slot therebetween, said surfaces being parallel to the prescribed path of said finger member and facing said first surface of said actuator to permit said actuator to freely move into said first slot when said finger member is in its unoperated position without disturbing said card from its unoperated position, said finger member being arranged to extend across the first slot of said card when said finger member is in its operated position such that upon movement of said actuator to its operated position, said operated finger member is trapped between said first surface of said actuator and said surfaces of said card thereby causing said card to move to its operated position, said movable contact is tensioned against said other contact, said card has a second slot therein containing the movable contact such that one wall thereof keeps the contacts apart when said card is in its unoperated position and allows them to mate when said card is in its operated position.

4. A device as defined in claim 3 wherein said actuator includes a shoulder extending at right angle from said surface toward said card such that said shoulderwill move into said first slot of said card when said finger member is in its unoperated position, said shoulder determining the extent of the predetermined distance of movement of said finger member when it is moved to its operated position.

5. An electrical contact actuating device for use in a crossbar switch comprising:

(a) first and second pairs of electrical contacts, each pair having one contact movable to mate with the other;

(b) a pair of like contact actuating cards each card cooperating with said one contact of an associated pair, each said card having an unoperated and an operated position and being movable between said positions through a prescribed path that intersects its associated one contact such that each pair of contacts are spaced apart when its associated card is in its unoperated position and each pair of contacts mates when its associated card is in its operated position, said cards being arranged in spaced parallel relation;

(0) an actuator having an unoperated and an operated position and being movable between said positions through a prescribed path parallel to the prescribed paths of said cards;

((1) a support member and first and second elongated resilient finger members each having one end attached to the support member and extending therefrom in separated parallel relation, each said finger member having its shank interposed between said actuator and said cards across their prescribed paths, each said finger member having an unoperated and an operated position and being movable a predetermined distance between said positions in opposite directions to each other through a prescribed path at substantially a right angle to the prescribed paths of said actuator and said cards;

( e) control means mounted independently of said finger members comprising a movable bar having an unoperated position and arranged to rotate about its longitudinal axis in one direction and in the opposite direction to said one direction to two operated positions, and an elongated rigid member having one end attached to the movable bar such that it will rotate with rotation of the movable bar, said finger members being located in the path of rotation of said rigid member, such that said first and second finger members are flexed from their unoperated to their operated positions upon rotation of the movable member from its unoperated position in said one and opposite directions respectively;

(f) said actuator and said cards having surface means for cooperation with said finger members, such that said actuator when moved from its unoperated to its operated position will not engage either-of said finger members when in its unoperated position, movement of said actuator from its unoperated to its operated position will trap either said finger member when in its operated position between said actuator and its associated card to cause said associated card to move from its unoperated to its operated position, and movement of either said finger member from its unoperated to its operated position once said actuator is in its operated position will permit said finger member to move substantially said predetermined distance without engaging its associated card.

6. A device as defined in claim wherein the surface means of said actuator comprises a. first pair of surfaces parallel to the prescribed paths of said finger members, each surface of said pair facing an associated said card for trapping an associated finger member between its associated card and said actuator when said finger member is in its operated position and said actuator is then moved from its unoperated to its operated position, and a second pair of surfaces each extending from its associated first surface and extending away from its associated card from a position adjacent to but spaced from the unoperated positions of an associated said finger member in a direction toward the operated position of the associated said finger member to permit each said finger member to move substantially said predetermined distance along its associated said second surface, said second surfaces being joined by a third surface at locations re mote from the juncture of associated first and second surfaces to define a cavity extending toward said third surface, said finger members in their unoperated positions being located facing said cavity to permit movement of said actuator to its operated position past. said finger members without engaging them, said finger members occupying said cavity.

7. A device as defined in claim 6 wherein the surface means of each said card comprising two coplanar flat surfaces with a first slot therebetween, each said surface being parallel to the prescribed path of its associated said finger member and facing'its associated first surface of said actuator to permit said actuator to freely move into said first slot of each card when its associated finger member is in its unoperated position without disturbing said card from its unoperated position, each said finger member being arranged to extend across the first slot of its associated card when said finger member is in its operated position, such that upon movement of said actuator to its operated position, said operated finger member is trapped between the associated first surface of said actuator and said surfaces of said card thereby causing said card to move to its operated position, wherein the movable contact of each said pair is tensioned against its associated other contact, each said card has a second slot therein containing its movable contact such that one wa l thereof keeps the contacts apart when said card is in its unoperated position and allows them to mate when said card is in its operated position.

8. A device as defined in claim 7 wherein said actuator includes a pair of shoulders each extending at a right angle from an associated first surface toward its associated card such that each said shoulder will move into said first slot of its associated card when said finger member is in its unoperated position, each said shoulder determining the extent of the predetermined distance of movement of its associated finger member when it is moved to its operated position.

9. A switch as defined in claim 1 wherein the rigid member is substantially L-shaped, with the base of the L resting against the, finger member when the movable bar is in its unoperated position, whereby when the movable bar returns to its unoperated position after rotation in said one direction, and when the actuating means returns to its unoperated position, the rigid member will damp the tendency of the finger member to vibrate.

10. A .switch as defined in claim 5 wherein the rigid member is substantially L-shaped, with the base of the L resting against each finger member when the movable bar is in its unoperated position, whereby when the movable bar returns to its unoperated position after rotation in either direction, the rigid member will damp the tendency of either finger member to vibrate.

11. A switch as defined in claim 5 wherein the switch is a communications crossbar switch, the movable'bar being the select bar of the crossbar switch arranged to rotate in said one and opposite directions in response to operation of a pair of select magnets, the actuator being part of a vertical sub-assembly of the crossbar switch and arranged to operate in response to operation of its associated hold magnet.

12. A switch as. defined in claim 7 wherein each card has a plurality of second slots, each said slot having a pair of contacts whereby movement of the card by the actuator causes each pair of contacts to mate.

References Cited UNITED STATES PATENTS 4/1938 Magrath ZOO-17! 1/1940 Stockfleth 335- ll2 X 

